One kind of 3-(substituted dihydroisoindolinone-2-yl)-2,6-dioxopiperidine, in particular 3-(4-amino-1-oxo-1,3-dihydro-2H-isoindole-2-yl)-piperidine-2,6-dione was disclosed in the article “Amino-substituted thalidomide analogs: Potent inhibitors of TNF-α production” (Muller etc., Bioorganic & Medicinal Chemistry Letters, Vol. 9, Issue 11, 7 Jun., 1999: pp 1625-1630) and Chinese Patent ZL97180299.8. In December 2005, 3-(4-amino-1-oxo-1,3-dihydro-2H-isoindole-2-yl)-piperidine-2,6-dione was approved as a kind of immunomodulator with anti-tumor activities, indicated for the treatment of myelodysplastic syndromes and multiple myeloma.
The diseases and syndromes which can be treated by 3-(4-amino-1-oxo-1,3-dihydro-2H-isoindole-2-yl)-piperidine-2,6-dione include, but are not limited to: myeloproliferative disorder, myelodysplasia syndrome, vasculogenesis, cancer, pain, macular degeneration, asbestosis, anaemia, nervous system disease, dyssomnia, dermatosis, pulmonary hypertension, immune deficiency disorder, parasitic diseases, central lesion etc., namely that were described in the following Chinese Patents with the application numbers, which are incorporated herein in their entirety by reference: 97180299.8, 98805614.3, 03825761.0, 03825567.7, 03813733.X, 03816899.5, 200610150484.3, 200380107531.0, 200710103924.4, 200380108093.X, 200380108398.0, 200480043341.1, 200480038171.8, 200480035556.9, 200480020445.0, 200480043535.1, 200480040004.7, 200480041252.3, 200480042208.4, 200580017546.7, 200580016344.0, 200580020628.7, 200580037220.0, 200580047364.4, 200580046371.2, 200580047031.1 etc.
Eight polymorphs of 3-(4-amino-1-oxo-1,3-dihydro-2H-isoindole-2-yl)-piperidine-2,6-dione and the preparation methods thereof were described by the US Celgene Corporation in the Chinese Patent CN 1871003A (publication number). By the methods, 3-4-amino-1-oxo-1,3-dihydro-2H-isoindole-2-yl)-piperidine-2,6-dione was added into water or organic solvent (e.g. hexane, toluene, acetone, acetonitrile, methanol, ethyl acetate) where it is practically insoluble, and then was dissolved by heating. It will crystallize when being cooled or crystal transform when being stirred for long time in slurrying system of solid-liquid diphase.
Because 3-(4-amino-1-oxo-1,3-dihydro-2H-isoindole-2-yl)-piperidine-2,6-dione is practically insoluble in water or organic solvent (e.g. hexane, toluene, acetone, acetonitrile, methanol, ethyl acetate etc.), even in the condition of heating, a large amount (over 100 times) of solvent is needed, which is disadvantageous in industrial production; in addition, with the method described in the Patent CN 1871003A, the appearance, color and luster of the products can not be improved from light yellow to white or off-white; also, it was not taken into consideration that harmful organic solvent sorted in or above class II (e.g. toluene and acetonitrile etc.) should be tried not to use in synthesis of final products to minimize the negative effects of the residual organic solvent in products on human body.
In terms of polymorphs of drug, each polymorph has different chemical and physical characteristics, including melting point, chemical stability, apparent solubility, rate of dissolution, optical and mechanical properties, vapor pressure as well as density. Such characteristics can directly influence the work-up or manufacture of bulk drug and formulation, and also affect the stability, solubility and bioavailability of formulation. Consequently, polymorph of drug is of great importance to quality, safety and efficacy of pharmaceutical preparation. When it comes to 3-(4-amino-1-oxo-1,3-dihydro-2H-isoindole-2-yl)-piperidine-2,6-dione, there are still needs in the art for new polymorphs suitable for industrial production and with excellent physical and chemical properties as well.